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This study used a multi‐model ensemble (MME) simulation to project changes in extreme precipitation (EP) over the next century based on four relevant indexes (R95P, FRE, total precipitation [PRCPTOT] and PPER) during the monsoon period (May–September) over eastern Asia. The ensemble model was built from three global climate models from the Coupled Model Inter‐comparison Project Phase 5. The results indicate that the MME results can reproduce observations of the spatial distribution characteristics of EP indexes in eastern Asia. Compared with the reference period of 1986–2005, the EP (R95P), PRCPTOT and the ratio of EP to PRCPTOT (PPER) in eastern Asia will increase during the monsoon period under the three emission scenarios in three durations (the early period: 2020–2039, middle period: 2050–2069 and late period: 2080–2099) throughout the 21st century. This feature is especially strong in southeast China and the Malay Islands. Meanwhile, the variation in the frequency of EP events (FRE) has prominent regional differences, including a decrease in the Yellow River Basin and the Indochina Peninsula and an increase in southeast China. All projected increasing were most significant under high emissions (RCP8.5). This study also suggests that EP would not generally increase in frequency but rather in intensity. With an increase in emissions concentration, the temperature threshold at which EP occurs is likely to rise, so the EP might need triggered by the higher temperatures. [ABSTRACT FROM AUTHOR]

Local moisture recycling (precipitation recycling) plays a crucial role in precipitation. However, evapotranspiration, the key to precipitation recycling, is difficult to estimate. In this study, restrictions between the evapotranspiration ability and soil moisture (SM) supply are considered, and evapotranspiration estimations from 1981 to 2010 in Afro-Eurasia are examined. The results show that the improved evapotranspiration estimation obtained by correcting the potential evapotranspiration in Afro-Eurasia, especially in the Asia-Africa arid regions, ranges from 0.2 to 1.2 mm day−1, which was less than that obtained using the traditional Penman-Monteith evapotranspiration (PET, which ranges from 1.0 to approximately 11.0 mm day−1). Based on different evapotranspiration estimations, the characteristics of the precipitation recycling ratio (PRR) calculated using the dynamic recycling model (DRM) are analyzed and compared for three arid regions in the Asian-African continent, China-Mongolia (CM), West Asia (WA), and North Africa (NAF), during the precipitation season. A comparison with the results from the PET method reveals that the estimated evapotranspiration and precipitation recycling obtained using the corrected approach was more reasonable than that obtained using the Penman-Monteith method. Overall, the PRR in CM (about 0.7%) and NAF (about 0.5%) shows decreasing trends, whereas the PRR in WA (about 1.0%) increased, which implies that because the local moisture supply increased in WA and reduced in CM and NAF, the drought intensity increased in WA but weakened in CM and NAF. This trend was partially related to increased precipitation recycling that occurred with increased evapotranspiration in WA. Moreover, the negative PRR trend and alleviated drought intensity in CM and NAF implied that precipitation recycling had a negative effect when there was less local moisture supply in the region, and this alleviated the drought intensity in the Asian-African arid regions. [ABSTRACT FROM AUTHOR]

Evaporation is a principal factor in the hydrological cycle and energy exchange; however, estimations of evaporation include large uncertainties. In this study, a modified estimation of evaporation based on empirical linearly simplified Penman evaporation (PES) is proposed, soil moisture and precipitation are used to correct the land surface evaporation estimation, and the temporal and spatial characteristics of the corrected evaporation (CE) are investigated globally. The results show that CE is strong at low latitudes and weak at high latitudes. CE has obvious seasonal variation, ranging from 0.2 to 4.0 mm day−1; CE is prominent in summer but feeble in winter. Compared to PES, CE is generally weaker in most regions, especially in arid regions, with differences of more than 9 mm day−1. CE agrees well with evaporation derived from FLUXNET-Model Tree Ensemble (FLUXNET-MTE), MERRA, and GLDAS. In general, the root-mean-square error (RMSE) between annual CE and FLUXNET-MTE is less than 0.2 mm day−1, and CE is about 5%–10% less than the evaporation of FLUXNET-MTE. In the arid regions, the maximum CE almost occurs in the month with the strongest precipitation; in the tropical regions, soil moisture enhances CE only when precipitation is less. In the context of global temperature rise, PES always shows an apparent increasing trend due to the water supply is not considered; however, CE decreases in western Asia, the western United States, the Amazon basin, and Central Africa, but weakly increases in the other study regions from 1984 to 2013. This study provides a method for estimating evaporation considering more restrictive factors on evaporation. [ABSTRACT FROM AUTHOR]

Soil moisture can be an effective climate prediction signal due to its long memory. This study investigated seasonal persistence of soil moisture anomalies from the preceding autumn to spring dominated by the soil freeze–thaw (FT) process over the Tibetan Plateau (TP), and their relationship with summer precipitation in eastern China. Results demonstrated that soil moisture anomalies from the preceding autumn can persist until spring by water storage effect of the soil FT process. Soil moisture in the TP during the preceding autumn and winter had similar climatic effects as spring soil moisture. Positive soil moisture anomalies in the eastern TP during the spring led to less summer precipitation in south China and the Yellow River basin, and more summer precipitation in the Yangtze River basin and northeast China. A possible mechanism for this was that wetter soil moisture anomalies from the preceding autumn were stored in the soil by soil freezing, and were released with soil thawing in the spring, inducing surface diabatic heating anomalies over the TP. These anomalies then persisted into summer and enhanced the TP's thermal forcing to the subtropical westerlies and affected stationary Rossby wave train propagation in middle latitudes, particularly on the northwest and northeast sides of the TP. This study suggests that most of spring soil moisture anomalies signal contains the preceding two seasons' soil moisture anomalies information; therefore, summer precipitation predicting signals can be obtained from soil moisture anomalies from the preceding autumn, which could lengthen the seasonal climate prediction period. [ABSTRACT FROM AUTHOR]

Sudden turn from drought to flood (STDF) is a unique representation of intra-seasonal extreme events and occurs frequently. However, it is notoriously difficult to represent in climate simulations due to the accumulation of model errors. This study uses a regional climate model (RCM) with different initialization and nudging schemes to explore effective approaches for capturing a STDF event. Results show that the conventional continuous integration with single initialization cannot reproduce the STDF event, while nudging or re-initialization can. Furthermore, spectral nudging and re-initialization outperform the conventional continuous simulation in reproducing precipitation features, but grid nudging induces the largest biases for precipitation though it has the smallest biases for other meteorological elements. Scale separation analysis shows that the large-scale features of the conventional continuous simulation drift far from the actual fields and force erroneous small-scale features, whereas the nudging and re-initialization successfully prevent the model from drifting away from the forcing fields at large-scales. The different performance for simulating precipitation among spectral nudging, re-initialization and grid nudging can be attributed to that the former two methods generate their own small-scale information via the RCM, while grid nudging over-suppresses the small-scale information while retaining the large-scale features. The difference in small-scale features affects the simulation of different moisture fluxes and convergences, as well as clouds, and then results in diverse precipitation. These results illustrate that both the consistency with large-scale features and the local variability from small-scale features are both robust factors for reproducing precipitation features during extreme events using RCMs. [ABSTRACT FROM AUTHOR]

Frequently occurring extreme precipitation events have caused severe disasters over the years, especially in monsoon regions such as Southeast Asia and East China (SAEC). Understanding the characteristics of extreme precipitation in SAEC on annual and monthly scales is essential for improving predictions extreme precipitation events. In this study, the temporal and spatial distribution characteristics of extreme precipitation events in the summer half‐year (May to September) are analysed from 1986 to 2015 over SAEC, based on the threshold of extreme precipitation defined with a percentile method and the daily precipitation data from 190 meteorological stations. The results indicate that the precipitation in annual and summer half‐year over the SAEC are mainly attributed to extreme precipitation events. The frequency and amount of extreme precipitation are significant in South China and Southeast Asia, the Yangtze River region, and North China; specifically, the duration of high extreme precipitation events are longer in South China and Southeast Asia compared to those in other areas. The frequency and amount of extreme precipitation increased in South China, Southeast Asia and North China while have a decreasing trend in Yangtze River basin. Further investigation of the possible relationship between summer extreme precipitation events and the activity of the Asian summer monsoon (ASM) indicate that, the movements of extreme precipitation are consistent with the northward advance and southward withdrawal of summer monsoon and are commonly located in the vicinity of the front of the ASM. This phenomenon suggests that summer extreme precipitation events over SAEC are closely connected with ASM activity and may be the products of ASM. The spatial distribution of (a) mean annual extreme precipitation (R95P), (b) mean annual extreme precipitation frequency, (c) annual total precipitation (PRCPTOT) and (d) the proportion of annual extreme precipitation to annual precipitation (PPER) over Southeast Asia and East China during 1986–2015. The black dots denote geographic distribution of 190 stations in Southeast Asia and East China. [ABSTRACT FROM AUTHOR]

Short-term climate prediction based on a regional climate dynamical model heavily depends on atmospheric forcing and initial soil moisture state. In this study, the Weather Research and Forecasting (WRF) Model with different nudging schemes is used for approximate 2-yr simulations for investigating the importance of soil variables in seasonal temperature and precipitation simulations. The results show that the improvement of seasonal climate simulation (precipitation and air temperature) is more evident in the experiment of assimilating both soil and atmospheric variables than that in the experiments of assimilating atmospheric variables only. Further investigation of the impact of indirectly assimilating soil moisture on precipitation prediction with an indirect soil nudging (ISN) scheme shows that the precipitation reproducibility in summer is better than that in winter, and the effect of ISN is particularly prominent in the region where seasonal precipitation exceeds 200 mm. Moreover, statistical results also illustrate that initial soil moisture plays a crucial role in seasonal precipitation forecasts because of its slowly evolving nature, and its effect is more distinct in semiarid and semihumid regions than in arid and humid regions. The effects of indirectly assimilating soil moisture on precipitation can last two and three months in semiarid and semihumid areas, respectively. [ABSTRACT FROM AUTHOR]

Changes of precipitation recycling (PR) in Northern Hemisphere from 1981 to 2010 are investigated using a water recycling model. The temporal and spatial characteristics of recycling in arid regions are analyzed. The results show that the regional precipitation recycling ratio (PRR) in arid regions is larger than in wet regions. PRR in arid regions has obvious seasonal variation, ranging from more than 25 % to less than 1 %. Furthermore, in arid regions, PRR is significantly negatively correlated with precipitation (correlation coefficient r = −0.5, exceeding the 99 % significance level). Moreover, the trend of PRR is related to changes in precipitation in two ways. PRR decreases with increasing precipitation in North Africa, which implies that less locally evaporated vapor converts into actual precipitation. However, in Asian arid regions, the PRR increases as precipitation reduces, which implies that more locally evaporated vapor converts into rainfall. Further, as PRR mainly depends on evapotranspiration, the PRR trend in Asian arid regions develops as temperature increases and more evaporated vapor enters the atmosphere to offset the reduced rainfall. [ABSTRACT FROM AUTHOR]

The statistical characteristics of the vertical structure of clouds in the Asian summer monsoon region are investigated using two CloudSat standard products (Geometrical Profiling Product (GEOPROF) and GEOPROF-lidar) during the pre- and post-onset periods of the Asian summer monsoon, from April to August in 2007-2010. The characteristics of the vertical structure of clouds are analyzed and compared for different underlying surfaces in four subregions during this period. Also analyzed are the evolution of precipitation and hydrometeors with the northward advance of the Asian summer monsoon, and different hydrometeor characteristics attributed to the underlying surface features. The results indicate that the vertical cloud amounts increase significantly after the summer monsoon onset; this increase occurs first in the upper troposphere and then at lower altitudes over tropical regions (South Asian and tropical Northwest Pacific regions). The heights of the cloud top ascend, and the vertical height between the top and the base of the whole cloud increases. Single-layer (SL) and double-layer (DL) hydrometeors contribute over half and one third of the cloudiness in these 5 months (April to August), respectively. The multilayer frequencies increase in four different regions, and cloud layer depths (CLD) increase after the summer monsoon onset. These changes are stronger in tropical regions than in subtropical regions, while the vertical distance between cloud layers (VDCL) deceases in tropical regions and increases in subtropical regions. [ABSTRACT FROM AUTHOR]

The characteristics of seasonal precipitation over the Tibetan Plateau (TP) were investigated using TRMM (Tropical Rainfall Measuring Mission) precipitation data (3B43). Sensitive regions of summer precipitation interannual variation anomalies were investigated using EOF (empirical orthogonal function) analysis. Furthermore, the profiles of cloud water content (CWC) and precipitable water in different regions and seasons were analyzed using TRMM-3A12 data observed by the TRMM Microwave Imager. Good agreement was found between hydrometeors and precipitation over the eastern and southeastern TP, where water vapor is adequate, while the water vapor amount is not significant over the western and northern TP. Further analysis showed meridional and zonal anomalies of CWC centers in the ascending branch of the Hadley and Walker Circulation, especially over the south and east of the TP. The interannual variation of hydrometeors over the past decade showed a decrease over the southeastern and northwestern TP, along with a corresponding increase over other regions. [ABSTRACT FROM AUTHOR]

Summary This study calculated the annual and inter-annual variations in the precipitation recycling ratio (PRR) on the Qinghai–Xizang Plateau (QXP); and by using water mass balance equation; we evaluated the estimated evaporation in the area. The results indicate that the estimated evaporation relate strongly to surface air temperature, relative humidity and wind speed. As temperatures on the QXP increase, the changes of PRR vary by regions within the plateau. Between 1979 and 2008, the PRR decreased in the western QXP, which is an arid area, but it increased in the other areas. The strongest increasing PRR trend is 3.1%/10 a in the northeastern QXP, but a decreasing trend, ranging downward to −2.5%/10 a, was observed in the western QXP. There is a significant seasonal change in precipitation recycling (PR) over QXP. The PR peak values occurred in July in all regions, and PR was very low (approaching 0.0) in winter half-year period. The monthly maximum PRR reached 0.62, which occurred in July over the southeastern QXP, where is a rich center of precipitation. These results imply that there is remarkable change of moisture resource of precipitation in last decades. On the QXP, large-scale moisture advances decrease with increased temperature, and the local moisture cycle is reinforced in wet regions. [ABSTRACT FROM AUTHOR]

In this article, the trends and variability of precipitation and precipitable water (PW) over the Qinghai-Xizang (Tibet) Plateau (QXP) (1970-2009) were analysed by using ERA-40 (The European Center for Medium-Range Weather Forecasts (ECMWF) 40 years Re-analysis) and NCEP (The National Centers for Environmental Prediction)/NCAR reanalyses data and the ground observed precipitation data from 60 sites. The results showed that the precipitation over the QXP had an overall increasing trend; however, a slight decreasing trend was observed over the southeast. This decreasing precipitation trend might be related to the South Asia monsoon degradation. Since 1970, a decreasing PW trend has occurred over the QXP in which the southeast is the most significant region. Because of the rising temperatures in the QXP, a remarkable PW conversion rate (PWCR) increase of 0.87% per decade has occurred over the past 40 years. Because of its steep terrain, the PWCR in the middle eastern region of the QXP increased faster than that of the other regions. The mean PWCR in the wet southern region of the QXP was higher than that of the dry northern region, which was higher in the winter than that in the summer. Although much precipitation occurred in the summer, in the wet regions, the PWCR was higher in the winter than in the summer. The PWCR peak in the wet and dry regions occurred during the precipitation-short and precipitation-sufficient seasons, respectively. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the soil freeze/thaw phenomenon, the soil water phase and energy budget change, which can affect the land-atmosphere system. Herein, the role of freeze–thaw–process (FTP) in soil water and heat transport and its effects on soil moisture variation were investigated using the observations and numerical experiments on the Tibetan Plateau (TP). The seasonal persistence of soil moisture anomalies related to soil FTP over TP and relationship with summer precipitation in Eastern China (EC) were also analyzed. The results revealed that no soil FTP (i.e., no water phase change occurred) resulted in drier surface soil moisture is drier by about -0.02 mm3/mm3, reduced by ~10% as a result of enhanced evaporation in after-thaw (AT) period (spring). Soil FTP has a water storage effect, and the storage index (SI) can reach 0.95 at surface layer. Without soil FTP, the soil moisture memory was shortened by about -20 days in March. Soil moisture anomalies from the preceding autumn can be retained to the spring by water storage effect of soil FTP. The soil moisture over the TP during the preceding autumn and winter had the similar climatic effects as spring soil moisture. The wetter soil moisture anomalies in the eastern TP in the spring led to less summer precipitation in south China and the Yellow River basin, and more summer precipitation in the Yangtze River basin and northeast China. Our results suggested that the information related to soil FTP can provide "signal" of seasonal climate prediction. [ABSTRACT FROM AUTHOR]

A short‐lived (less than 2 days) inner Tibetan Plateau vortex (TPV) with heavy precipitation was simulated using the Weather Research and Forecasting model, and the sensitivity experiments with and without surface diabatic heating and atmospheric latent heating released by precipitation were conducted to investigate the roles of surface and atmospheric diabatic heating on the genesis and development of TPV. Results show that before the genesis of the TPV, there is an anomalous increase of surface heating flux; while a disturbance of potential vorticity (PV) at 500 hPa moves over this region, the PV is enhanced and induces the generation of TPV. The precipitation in turn reduces the surface heating flux. The release of condensation latent heating by precipitation during the development of TPV does not further contribute to its reinforcement. Instead, it is more likely a result of precipitation, tending to stabilize the atmosphere and conducive to the decay of TPV. The PV diagnoses further reveal that in the early phase, the strong diabatic heating in the lower levels associated with the increasing surface heating flux has a significantly positive contribution to the generation of the TPV. The precipitation results in the decrease of positive diabatic heating contribution at low levels. Inversely, the diabatic heating in the middle levels associated with the released latent heating of precipitation condensation tends to have the negative contribution to TPV, resulting in the decay of TPV. The study of this case can deepen our understanding on the mechanism of TPV and its precipitation. Key Points: The surface diabatic heating prior to the precipitation is crucial to the formation of TPVThe condensation latent heating caused by precipitation only seems to be a result of precipitation [ABSTRACT FROM AUTHOR]